Thermodynamic of universe with a varying dark energy component

TL;DR

This paper explores how a varying dark energy component influences the thermodynamics of the universe, particularly the apparent horizon entropy, and examines the effects of interactions between cosmic sectors on thermodynamic laws.

Contribution

It introduces a model where dark energy modifies horizon entropy and extends the analysis to interacting sectors, revealing additional entropy contributions and thermodynamic law implications.

Findings

Dark energy can alter the apparent horizon entropy and the Bekenstein limit.

Interactions between cosmic sectors add extra terms to horizon entropy.

The second law of thermodynamics remains valid in both interacting and non-interacting models.

Abstract

We consider a FRW universe filled by a dark energy candidate together with other possible sources which may include the baryonic and non-baryonic matters. Thereinafter, we consider a situation in which the cosmos sectors do not interact with each other. By applying the unified first law of thermodynamics on the apparent horizon of the FRW universe, we show that the dark energy candidate may modify the apparent horizon entropy and thus the Bekenstein limit. Moreover, we generalize our study to the models in which the cosmos sectors have a mutual interaction. Our final result indicates that the mutual interaction between the cosmos sectors may add an additional term to the apparent horizon entropy leading to modify the Bekenstein limit. Relationships with previous works have been addressed throughout the paper. Finally, we investigate the validity of the second law of thermodynamics and its generalized form in the interacting and non-interacting cosmoses.